Methods and apparatus for polishing an edge of a substrate

ABSTRACT

Methods, systems and apparatus are provided for polishing an edge of a substrate. The invention includes an apparatus adapted to apply a preset pressure to a polishing film in contact with an edge of a substrate. The apparatus includes an actuator adapted to apply a preset pressure to the polishing film; and a controller coupled to the actuator and adapted to receive a signal indicative of a condition of the edge of the substrate, and to adjust a pressure applied by the actuator to the polishing film so as to maintain the preset pressure based on the received signal. Numerous other aspects are provided.

This application is a division of, and claims priority to, U.S.Non-Provisional patent application Ser. No. 11/693,695, filed Mar. 29,2007, and titled, “METHODS AND APPARATUS FOR POLISHING AN EDGE OF ASUBSTRATE” (Attorney Docket No. 10560), which claims priority to U.S.Provisional Patent Application Ser. No. 60/787,438, filed Mar. 30, 2006,and entitled “METHODS AND APPARATUS FOR PROCESSING A SUBSTRATE”(Attorney Docket No. 10560/L). Both of these patent applications areincorporated by reference herein in their entirety for all purposes.

CROSS-REFERENCE TO RELATED APPLICATIONS

Further, the present application is related to the followingcommonly-assigned, co-pending U.S. patent applications, each of which ishereby incorporated herein by reference in its entirety for allpurposes:

U.S. patent application Ser. No. 11/298,555 filed on Dec. 9, 2005 andentitled “METHODS AND APPARATUS FOR PROCESSING A SUBSTRATE” AttorneyDocket No. 10414); and

U.S. patent application Ser. No. 11/299,295 filed on Dec. 9, 2005 andentitled “METHODS AND APPARATUS FOR PROCESSING A SUBSTRATE” (AttorneyDocket No. 10121).

FIELD OF THE INVENTION

The present invention relates generally to substrate processing, andmore particularly to methods and apparatus for polishing an edge of asubstrate.

BACKGROUND OF THE INVENTION

Conventional systems, which contact a substrate edge with an abrasivefilm to clean the edge, may not thoroughly polish or clean the edge. Forexample, the abrasive film may not sufficiently contact both bevels ofthe edge during cleaning. Additionally, the abrasive film may becomeworn from use, and therefore, lose its ability to sufficiently clean thesubstrate and require frequent replacement, which may affectsemiconductor device manufacturing throughput. Accordingly improvedmethods and apparatus for cleaning an edge of a substrate are desired.

SUMMARY OF THE INVENTION

In a first aspect of the invention, a method of polishing an edge of asubstrate is provided. The method includes (1) rotating a substrateagainst a polishing film so as to remove material from the edge of thesubstrate and (2) detecting an amount of one of energy and torqueexerted in rotating the substrate against the polishing film.Embodiments of the method further include (3) determining an amount ofmaterial removed from the edge of the substrate based on the detectedenergy or torque exerted in rotating the substrate against the polishingfilm; (4) ascertaining a difference between the determined amount ofmaterial removed and a preset polish level; and (5) determining anamount of energy or torque to be exerted in rotating the substrateadapted to attain the preset polish level based on the differencebetween the determined amount of material removed and the preset polishlevel.

In a second aspect of the invention, an alternative method of polishingan edge of a substrate is provided. The method includes (1) rotating asubstrate against a polishing film so as to remove material from theedge of the substrate and (2) detecting an amount of force exerted inpressing the polishing film against the substrate. Embodiments of themethod include (3) determining an amount of material removed from theedge of the substrate based on the detected force exerted in pressingthe polishing film against the rotating substrate; (4) ascertaining adifference between the determined amount of material removed and apreset polish level; and (5) determining a level of force to be appliedto the polishing film adapted to attain the preset polish level based onthe difference between the determined amount of material removed and thepreset polish level and adjusting the force to the determined level.

In a third aspect of the invention, a system adapted to polish an edgeof a substrate comprising is provided. The system includes (1) asubstrate rotation driver adapted to rotate the edge of a substrateagainst a polishing film and (2) a first sensor coupled to the rotationdriver adapted to detect one of an energy and torque exerted by thesubstrate rotation driver as it rotates the substrate against thepolishing film. Embodiments of the system further include (3) acontroller coupled to the first sensor and to the substrate rotationdriver adapted to receive from the first sensor a signal indicative ofthe detected energy or torque exerted by the substrate rotation driverand adapted to transmit control signals to the substrate rotation driverbased on the detected energy or torque exerted.

In a fourth aspect of the invention, an apparatus adapted to apply apreset pressure to a polishing film in contact with an edge of asubstrate is provided. The apparatus includes (1) an actuator adapted toapply a preset pressure to the polishing film and (2) a controllercoupled to the actuator and adapted to receive a signal indicative of acondition of the edge of the substrate, and to adjust a pressure appliedby the actuator to the polishing film so as to maintain the presetpressure based on the received signal.

Other features and aspects of the present invention will become morefully apparent from the following detailed description, the appendedclaims and the accompanying drawings.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a schematic illustration of a cross-section of a portion of asubstrate.

FIG. 2 is a schematic illustration depicting an example embodiment of anedge cleaning apparatus according to the present invention.

FIGS. 3A and 3B are close-up front and side cross-sectional schematicviews, respectively, of a portion of the edge cleaning apparatus of FIG.2.

FIG. 4 is a perspective view depicting an example embodiment of an edgecleaning apparatus according to the present invention.

FIG. 5 is a perspective view depicting another example embodiment of anedge cleaning apparatus according to the present invention.

FIG. 6 is a perspective view of a portion of the example embodimentdepicted in FIG. 5.

FIGS. 7A and 7B are close-up perspective views of different embodimentsof replaceable cassettes for use with embodiments of the presentinvention.

FIGS. 8A through 8C are close-up perspective views of differentembodiments of pads for use with embodiments of the present invention.

FIGS. 9A through 9C are plan views of examples of different possiblehead positions of the example edge polishing apparatus of FIG. 4.

FIGS. 10A through 10C are plan views of examples of different possiblehead positions of the example edge polishing apparatus of FIG. 5.

FIG. 11 is a perspective view of an embodiment of a multiple head edgepolishing apparatus according to the present invention.

FIG. 12 is a perspective view of another embodiment of a multiple headedge polishing apparatus according to the present invention.

FIG. 13 is a perspective view of yet another embodiment of a multiplehead edge polishing apparatus according to the present invention.

FIG. 14 is a schematic illustration depicting an example embodiment ofan edge cleaning apparatus according to the present invention.

DETAILED DESCRIPTION

The present invention provides improved methods and apparatus forcleaning and/or polishing the edge of a substrate. With reference toFIG. 1, a substrate 100 may include two major surfaces 102, 102′ and anedge 104. Each major surface 102, 102′ of the substrate 100 may includea device region 106, 106′ and an exclusion region 108, 108′. (Typicallyhowever, only one of the two major surfaces 102, 102′ will include adevice region and an exclusion region.) The exclusion regions 108, 108′may serve as buffers between the device regions 106, 106′ and the edge104. The edge 104 of a substrate 100 may include an outer edge 110 andbevels 112, 114. The bevels 112, 114 may be located between the outeredge 110 and the exclusion regions 108, 108′ of the two major surfaces102, 102′. The present invention is adapted to clean and/or polish theouter edge 110 and at least one bevel 112, 114 of a substrate 100without affecting the device regions 106, 106′. In some embodiments, allor part of the exclusion regions 108, 108′ may be cleaned or polished aswell.

The present invention provides a frame for supporting a film (e.g., anabrasive polishing film) or abrasive buffer against the edge 104 of asubstrate 100 as the substrate 100 is rotated (e.g., by a vacuum chuck,drive rollers, etc.). The film may be pressed against the rotatingsubstrate edge 104 using a pad pushed by an actuator and/or aninflatable pad. In either case, the pad and/or inflatable pad may besoft and/or include or develop contours to conform with the shape of thesubstrate edge 104. Depending on the amount of force applied by theactuator, the resiliency of the pad selected, the amount of inflation ofan inflatable pad, and/or the amount of tension on the film, acontrolled amount of pressure may be applied to polish the edge 104.Alternatively or additionally, the film may be under tension within theframe such that the film itself is adapted to apply a variable amount oftension to the substrate edge 104 and to contour to both the outer edge110 and at least one of the bevels 112, 114 (e.g., with or withoutadditional support from a pad). Thus, the present invention providesprecise control of an edge polish process which may be used tocompensate for different edge geometries and changes in the substrate100 as material is removed from the edge 104.

In some embodiments, the frame may support multiple polishing heads,each head being adapted to support polishing film. The polishing headsmay support different types of films (e.g., films of different abrasivegrits) which may be used concurrently, in a predefined sequence, or atdifferent times. The heads may be disposed in different positions and indifferent orientations (e.g., aligned with the edge 104, normal to theedge 104, angled relative to the edge 104, etc.) to allow the supportedfilms to polish different portions of the edge 104 of the rotatingsubstrate 100. The heads may be adapted to be oscillated or moved (e.g.,angularly translated about a tangential axis of the substrate 100 and/orcircumferentially relative to the substrate 100) around or along theedge 104 by the frame so as to polish different portions of the edge104. In some embodiments, the heads may continuously oscillate around oralong the rotating edge 104 of the substrate 100. Each head may includean indexed spool of film and/or be contained in a replaceable cassette.An indexed spool may allow a precise amount of film to be advanced toposition unused film for polishing. In some embodiments, two indexedspools may be used to allow film to be moved back and forth between thespools.

Additionally or alternatively, the present invention may includefacilities to deliver fluids to the substrate edge 104 being polished.In some embodiments, one or more channels may be provided to directchemicals or water to the substrate edge 104 to assist in the polishingand/or to wash away particles resulting from the polishing. Thechemicals may be sprayed directly onto the substrate 100, at thesubstrate/polishing film interface, and/or may be applied to and/orthrough the film and/or pad. The fluids may be sprayed from either orboth sides of the substrate 100 and the present invention may employgravity or suction to cause the runoff not to contaminate or contactother parts of the substrate 100 or apparatus of the invention. Further,energy (e.g., megasonic energy) may be applied to the substrate edge 104via fluid carrying such energy.

The substrate 100 may be rotated in a horizontal plane. The edge 104 ofthe substrate 100 may be aligned with or normal to the polishing film,pad, and/or polishing head. In additional or alternative embodiments,the substrate 100 may be rotated in a vertical plane, othernon-horizontal plane, and/or be moved between different planes ofrotation.

In some embodiments, the driver(s) used to rotate the substrate 100 andthe actuator used to push the pad and/or polishing film against thesubstrate edge 104 may be controlled by a controller. Likewise,operation of the indexed spool(s) and/or the fluid channels may also beunder the direction of a controller. The controller may be adapted toreceive feedback signals from the driver and/or actuator that indicate:(1) an amount of energy and/or torque being exerted to drive thesubstrate 100 (e.g., rotate a vacuum chuck holding the substrate 100)and/or (2) an amount of force applied to the actuator to push thepad/polishing film against the substrate 100, respectively. Thesefeedback signals may be employed to determine an amount of material thathas been removed from the edge of the substrate 100, which may include,for example, whether a particular layer of material has been removedand/or whether an intended edge profile has been reached. For example, areduction in the torque of the rotating substrate 100 (or energyexpended in rotating the substrate 100) during a polishing procedure mayindicate a reduction in friction between the substrate 100 and thepolishing film and/or pad. The reduction in torque or rotational energymay correspond to an amount of material removed from the edge of thesubstrate 100 at or near points of contact between the substrate 100 andthe polishing film and/or a characteristic edge profile (e.g., a shape,curvature or smoothness level at the edge of the substrate 100).

Alternatively or additionally, a friction sensor positioned in contactwith the edge of the substrate may provide signals indicative of anamount of material that has been removed from the substrate 100.

Turning to FIG. 2, a schematic view of an edge polishing apparatus 200is depicted. A frame 202 supports and tensions a polishing film 204 in aplane perpendicular to the major surfaces 102, 102′ of a substrate 100such that the edge 104 of the substrate 100 may be pressed against(e.g., as indicated by the straight downward arrows 205 a, 205 b) thepolishing film 204 and the polishing film 204 may contour to thesubstrate edge 104. As indicated by the curved arrow 205 c, thesubstrate 100 may be rotated against the polishing film 204. Thesubstrate 100 may be rotated at a rate ranging from about 50 to 300 RPM,for example, although other rates may be used. The substrate 100 maycontact the polishing film 204 for about 15 to 150 seconds depending onthe type of film used, the grit of the film, the rate of rotation, theamount of polishing required, etc. More or less time may be used. Insome embodiments, the polishing film 204 may be supported by a pad 206disposed adjacent a backside (e.g., a non-abrasive side) of thepolishing film 204 and mounted on the frame 202. As indicated by thestraight upward pointing arrow 207, the frame 202 including thetensioned polishing film 204 and/or the pad 206 may be pushed againstthe edge 104 of the substrate 100. In some embodiments, the substrate100 may be pushed against the polishing film with an amount of forceranging from about 0.5 lbs. to about 2.0 lbs. Other amounts of force maybe used.

Additionally or alternatively, an additional length of the polishingfilm 204 may be supported and tensioned by spools 208, 210 mounted tothe frame 202. A supply spool 208 may include unused polishing film 204available to be unwound and pulled into position adjacent the substrate100 while a take-up spool 210 may be adapted to receive used and/or wornpolishing film 204. One or both of the spools 208, 210 may be indexed toprecisely control the amount of polishing film 204 that is advanced. Thepolishing film 204 may be made from many different materials includingaluminum oxide, silicon oxide, silicon carbide, etc. Other materials mayalso be used. In some embodiments, the abrasives used may range fromabout 0.5 microns up to about 3 microns in size although other sizes maybe used. The abrasives may also be of different shapes and textures.Different widths of polishing film 204 ranging from about 1 inch toabout 1.5 inches may be used (although other widths may be used). In oneor more embodiments, the polishing film may be about 0.002 to about 0.02of an inch thick and be able to withstand about 1 to 5 lbs. of tensionin embodiments that use a pad 206 and from about 3 to about 8 lbs. oftension in embodiments without a pad. Other films having differentthicknesses and strengths may be used. The spools 208, 210 may beapproximately 1 inch in diameter, hold about 500 inches of polishingfilm 204, and may be constructed from any practicable materials such aspolyurethane, polyvinyl difloride (PVDF), etc. Other materials may beused. The frame 202 may be constructed from any practicable materialssuch as aluminum, stainless steel, etc.

In some embodiments, one or more fluid channels 212 (e.g., a spraynozzle or bar) may be provided to deliver chemicals and/or water to aidin the polishing/cleaning of the substrate edge 104, lubricate thesubstrate, and/or to wash away removed material. The fluid channel 212may be adapted to deliver fluid to the substrate 100, to the polishingfilm 204, and/or to the pad 206. The fluids may include deionized waterwhich may serve as a lubricant and to flush particles away. A surfactantand/or other known cleaning chemistries may also be included. In someembodiments, sonic (e.g., megasonic) nozzles may be used to deliversonicated fluids to the substrate edge 104 to supplement the cleaning.Fluid also may be delivered through the polishing film 204 and/or pad206 to the edge 104.

Turning to FIGS. 3A and 3B, close-up front and side cross-sectionalschematic views, respectively, of the polishing film 204 and pad 206 ofFIG. 2 are depicted. Note that the forces (indicated by the straightarrows) cause the polishing film 204 and the pad 206 to contour andconform to the edge 104 of the substrate 100. In some embodiments, ifthe substrate 100 was not present, the pad 206 would have a flat surfacewhere the substrate 100 is shown compressing the pad 206. Likewise, ifthe substrate 100 was not present, the polishing film 204 would lie flatand be represented by a straight line in both views.

Turning now to FIGS. 4 and 5, two additional alternative embodiments ofan edge polishing apparatus 400, 500 are depicted. As shown in FIG. 4,an example edge polishing apparatus 400 may include a base or frame 402that includes a head 404 which supports polishing film 204 tensionedbetween spools 208, 210 and further supported by a pad 206. As shown,the pad 206 may by mounted to the head 404 via a biasing device 406(e.g., a spring). The edge polishing apparatus 400 of FIG. 4 also mayinclude one or more drive rollers 408 (two shown) and guide rollers 410(two shown) that are adapted to rotate the edge 104 of the substrate 100against the polishing film 204. The drive rollers 408 may themselveseach be driven by drivers 412 (e.g., motors, gears, belts, chains,etc.).

The drive rollers 408 and guide rollers 410 may include a groove thatallows the rollers 408, 410 alone to support the substrate 100. In someembodiments the groove within the drive rollers 408 may have a diameterof approximately 2.5 inches and the groove within the guide rollers 410may have a diameter of approximately 1 inch. Other dimensions arepossible. The area of the drive rollers 408 in contact with thesubstrate 100 may include texturing or cross-grooves to allow the driverollers 408 to grip the substrate 100. The drive rollers 408 and guiderollers 410 may be constructed from materials such as polyurethane,polyvinyl difloride (PVDF), etc. Other materials may be used.

As shown in FIG. 5, another example edge polishing apparatus 500 mayinclude a base or frame 502 that includes a head 504 which supportspolishing film 204 tensioned between spools 208, 210 and furthersupported by a pad 206. As shown, the pad 206 may by mounted to the head504 via an actuator 506 (e.g., a pneumatic slide, hydraulic ram, servomotor driven pusher, etc.). The edge polishing apparatus 500 of FIG. 5also may include a vacuum chuck 508 coupled to a driver 510 (e.g.,motor, gear, belt, chain, etc.). An advantage of the embodiment depictedin FIG. 5 is that the apparatus 500 does not need to contact the edge104 being polished. Thus, the potential of particles accumulating ondrive rollers and being re-deposited on the edge 104 is eliminated. Theneed to clean rollers also is eliminated. Further, the possibility ofrollers damaging or scratching the edge is also eliminated. By holdingthe substrate in a vacuum chuck, high speed rotation without significantvibration may be achieved.

Turning now to FIGS. 6 through 8B, some details of features of theexample embodiments of FIGS. 4 and 5 are described. Note that featuresfrom the different embodiments may be combined in many differentpracticable ways to serve different design principals or concerns.

FIG. 6 depicts details of the frame 502 including the head 504 of FIG.5. As described above, a head 504 supports polishing film 204 tensionedbetween spools 208, 210. The frame 502 (that includes head 504) may beadapted to be angularly translated (relative to an axis that istangential to the edge 104 of a substrate 100 held in the edge polishingapparatus 500 (FIG. 5)) by a driver 600 (e.g., a servo motor) and pivot602. The angular translation of the frame (and polishing film 204) isdescribed in more detail below with respect to FIGS. 9A through 10C.

Additionally, the spools 208, 210 that are mounted to the head 504, maybe driven by one or more drivers 604 (e.g., servo motors). The drivers604 may provide both an indexing capability to allow a specific amountof unused polishing film 204 to be advanced or continuously fed to thesubstrate edge, and a tensioning capability to allow the polishing filmto be stretched taught and to apply pressure to the substrate edge.

As can more clearly be seen in FIG. 6 (as compared to FIG. 5), theoptional pad 206 may by mounted to the head 504 via an actuator 506 thatis adapted to adjustably press and contour the polishing film 204against a substrate edge 104 (FIG. 5). Further, one or more supportrollers 606 may also be mounted to the head 504 to guide and align thepolishing film 204 in a plane perpendicular to the major surface 102(FIG. 1) of a substrate 100 held in the edge polishing apparatus 500(FIG. 5).

Note that in the embodiment depicted in FIGS. 5 and 6, the length of thepolishing film 204 is disposed orthogonal to the edge 104 of a substrate100 being polished. This is in contrast to the embodiment depicted inFIG. 2, wherein the longitudinal direction of the polishing film 204 isaligned with the edge 104 of a substrate 100 being polished. Otherpolishing film orientations and configurations may be employed. Forexample, the polishing film 204 may be held diagonally relative to themajor surface 102 of the substrate 100.

Turning to FIGS. 7A and 7B, close-up perspective views of two differentembodiments of replaceable cassettes 700A, 700B are depicted. Cassettes700A, 700B may be adapted to provide the features of the head 404 andpolishing film 204 in a disposable, refillable, and/or replaceablepackage which may be quickly and easily mounted on and/or removed fromthe frames 402, 502 of different edge polishing apparatuses 400, 500.

As shown in FIG. 7A, the cassette 700A may include head 404 whichsupports polishing film 204 which spans from supply reel 208 to take-upreel 210. The polishing film 204 may be guided and aligned by supportrollers 606 mounted to the head 404. A pad 206 may be provided tofurther support the polishing film 204 as described above. Also asdescribed above, a biasing device 406 (e.g., a spring) may be employedto mount the pad 206 to the head 404 to provide flexible, dynamiccounter-pressure to the pad 206. Alternatively or additionally, anadjustable actuator 506 (FIG. 6) may be used to push the pad 206 againstthe polishing film 204 or to push the entire head 404 toward thesubstrate 100.

In yet another alternative embodiment, as shown in FIG. 7B, instead of apad 206, the head 404 may simply rely on the tension of the polishingfilm 204 to provide lateral pressure to the substrate edge 104 (FIG. 1).In some embodiments, the head 404 may include a notch 702 as shown inFIG. 7B to accommodate the substrate 100.

Turning to FIGS. 8A and 8B, two different alternative embodiments ofpads 206A, 206B are depicted. In addition to a pad 206 (FIG. 6) that hasa flat surface co-planar with the polishing film 204 when a substrate isnot present, a pad 206A may include a concave surface that matches thecontour of the edge 104 of a substrate 100. Alternatively, as shown inFIG. 8B, the pad 206B may include a double concave surface to bettermatch the contour of the edge 104 of a substrate 100. In yet otheralternative embodiments, a pad 206 may include a shaped groove thatprecisely matches the contour of the edge 104 of a substrate 100including the bevels 112, 114 and outer edge 110 (FIG. 1).

The pads 206, 206A, 206B may be made of material such as, for example,an acetal resin (e.g., Delrin® manufactured by DuPont Corporation),PVDF, polyurethane closed cell foam, silicon rubber, etc. Othermaterials may be used. Such materials may have a resilience or anability to conform that is a function of the thickness or density of thepad. The material may be selected based upon its resilience, which, inturn, may be selected based upon the type of polishing required.

In some embodiments, the pad 206, 206A, 206B may have an adjustableamount of ability to conform to the substrate's edge. For example thepad 206, 206A, 206B may be or include an inflatable bladder such that byadding more air or liquid or other fluid, the pad becomes harder and byreducing the amount of air or liquid or other fluid in the bladder, thepad becomes more conforming. FIG. 8C depicts an embodiment of a pad 206Cthat includes an inflatable bladder 802 that may be filled (and/oremptied) via a fluid channel 804 with fluid from a fluid supply 806. Insome embodiments, the fluid supply 806 may inflate/deflate the bladder802 under the direction of an operator or a programmed and/or useroperated controller. In such embodiments, an elastomeric material suchas silicon rubber or the like, may be used for the bladder 802 tofurther enhance the pad's ability to stretch and conform to thesubstrate's edge 104. Such an embodiment would allow anoperator/controller to precisely control how far beyond the bevels 112,114 (if at all) and into the exclusion region 108 and/or 108′ (FIG. 1)the polishing film 204 is made to contact the substrate 100 by, e.g.,limiting the amount of fluid pumped into the bladder 802. For example,once a substrate outer edge 110 is placed against a pad 206C with adeflated bladder 802, the bladder 802 may be inflated so that the pad206C is forced to wrap around and conform to the outer edge 110 andbevel(s) 112, 114 of the substrate 100 without wrapping around to thedevice region 106, 106′ of the substrate 100. Note that in someembodiments, multiple bladders may be used in a pad and that differentlyshaped inflatable bladders may be used within differently shaped pads206, 206A, 206B.

In some embodiments, fluids used to aid in the polishing may bedelivered to the substrate edge via the pads 206, 206A, 206B. A fluidchannel may be provided to drip or spray the fluid on or into the pads.Alternatively, an inflatable pad may include a bladder with asemi-permeable membrane that allows fluid to be slowly released andtransmitted to the polishing film 204 (e.g., through the pad). In suchembodiments, the pads 206, 206A, 206B may be covered by, made of, and/orinclude material that absorbs and/or retains the fluids used (e.g.,polyvinyl alcohol (PVA), etc.).

FIGS. 9A through 9C and FIGS. 10A through 10C depict examples ofdifferent possible head positions of the alternative edge polishingapparatuses 400, 500 respectively, described above. The presentinvention is adapted to bring polishing film 204 in contact with thebevels 112, 114, and outer edge 110 of a substrate 100 withoutcontacting the device region 106 of the substrate 100. In operation,this is achieved by angularly translating a head 404, 504 (andconsequently, a portion of polishing film in contact with and contouredto the edge 104 of a substrate 100) around an axis that is tangential tothe outer edge 110 of the substrate 100 as it is rotated. Referring toFIGS. 9A through 9C and FIGS. 10A through 10C, this axis of angulartranslation may be represented by a line extending perpendicular out ofthe paper upon which the FIGs. are drawn at the point labeled “P.” Theheads 404, 504 may be held in various positions to clean desiredportions of the substrate edge 104 as the substrate 100 is rotated. Insome embodiments, the heads 404, 504 may be adapted to continuously orintermittently oscillate between the various positions depicted and/orother positions. The heads 404, 504 may be moved on the frame 502 bydrivers 600 (FIG. 6) under the direction of a programmed or useroperated controller. Alternatively, the heads 404, 504 may be fixedand/or only adjusted while the substrate is not being rotated. In yetother embodiments, the substrate may be held fixed while the heads areoscillated (as described above) as well as rotated circumferentiallyaround the substrate 100. Further, the polishing film 204 may be mountedon the heads 404, 504 in a continuous loop and/or the polishing film 204may be continuously (or intermittently) advanced to polish and/orincrease the polishing effect on the substrate edge 104. For example,the advancement of the film 204 may be used to create and/or enhance thepolishing motion. In some embodiments the film 204 may be oscillatedback and forth to polish and/or enhance the polishing effect on astationary or rotating substrate 100. In some embodiments, the film 204may be held stationary during polishing. Further, the film 204 tensionand/or force 207 (FIG. 2) may be varied based on various factorsincluding, for example, the angle and/or position of the polishing film204, the polishing time, the materials used in the substrate, the layerbeing polished, the amount of material removed, the speed at which thesubstrate is being rotated, the amount of current being drawn by thedriver rotating the substrate, etc. Any combination of the abovedescribed polishing motions and/or methods that are practicable may beemployed. These methods provide additional control over the edge polishprocess which can be used to compensate for geometry and changes in thematerial being removed as the film 204 is rotated/move about or relativeto the edge 104.

Turning to FIGS. 11 through 12, additional embodiments of an edgepolishing apparatus are depicted. FIG. 11 depicts an edge polishingapparatus 1100 including three heads 404, FIG. 12 depicts an edgepolishing apparatus 1200 including two heads 504, and FIG. 13 depicts anedge polishing apparatus 1300 including four heads 1304. As suggested bythe drawings, any number and type of heads 404, 504, 1304 may be used inany practicable combination. In addition, in such multi-headembodiments, each head 404, 504, 1304 may used a differently configuredor type of polishing film 204 (e.g., different grits, materials,tensions, pressures, etc.). Any number of heads 404, 504, 1304 may beused concurrently, individually, and/or in a sequence. Different heads404, 504, 1304 may be used for different substrates 100 or differenttypes of substrates. For example, a first head 404 with a stiff biasingdevice 406 supporting a pad 206 such as the concave pad 206B and acoarse grit polishing film 204 may initially be used to remove arelatively large amount of rough material from the substrate bevels 112,114 (FIG. 1). The first head 404 may be appropriately positioned toaccess the bevels 112, 114. After cleaning with the first head 404 iscompleted, the first head 404 may be backed away from the substrate 100,and a second head 504 with a fine grit polishing film 204 (and without apad) may be moved into position to polish the bevels 112, 114 and theouter edge 110.

After cleaning one or more substrates 100, the portion of the polishingfilm 204 employed for such cleaning may become worn. Therefore, thetake-up reel 210 (FIG. 4) may be driven to draw the polishing film 204by a fixed amount from the supply reel 210 (FIG. 4) toward the take-upreel 210. In this manner, an unused portion of the polishing film 204may be provided between the take-up reel 210 and supply reel 208. Theunused portion of the polishing film 204 may be employed to subsequentlyclean one or more other substrates 100 in a manner similar to thatdescribed above. Consequently, the apparatus 1100, 1200 may replace aworn portion of polishing film 204 with an unused portion with little orno impact on substrate processing throughput. Likewise, if replaceablecassettes 700A are employed, impact on throughput may be minimized byquickly replacing the cassettes 700A when all the polishing film 204 inthe cassette 700A is used.

Regarding the example embodiment of an edge polishing apparatus 1300 ofFIG. 13 specifically, a frame 1302 that supports multiple heads 1304 isdepicted in schematic form. The heads 1304 are each mounted to the frame1302 and each include an actuator 1306 (e.g., pneumatic piston, servodriven slide, hydraulic ram, etc.) adapted to press a pad 206 and alength of polishing film 204 against the edge 104 of a substrate 100 inresponse to a control signal from a controller 1308 (e.g., a programmedcomputer, an operator directed valve system, an embedded real timeprocessor, etc.). Note that the controller 1308 is coupled (e.g.,electrically, mechanically, pneumatically, hydraulically, etc.) to eachof the actuators 1306.

In addition, a fluid supply 806 may be coupled to and under the controlof the controller 1308. The fluid supply 806 may be controlled toindependently deliver fluids (e.g., DI water, cleaning chemistry,sonicated fluids, gas, air, etc.) to each of the heads 1304 via one ormore fluid channels 212. Under the direction of the controller 1308,various fluids may be selectively delivered to the pads 206, thepolishing film 204, and/or the substrate edge 104 via the fluid channels212. The fluid may be for use in polishing, lubricating, particleremoval/rinsing, and/or inflating a bladder 802 (FIG. 8C) within thepads 206. For example, in some embodiments, the same fluid deliveredthrough a permeable pad 206 may be used for both polishing and inflatingthe pad 206 while a different fluid, delivered to the same head 1304 viaa second channel (not shown) is used for rinsing and lubricating.

Turning to FIG. 14, a schematic view of an embodiment of the presentinvention similar to the example edge polishing apparatus 200 of FIG. 2is depicted. As with the embodiment of FIG. 2, a frame 202 supports andtensions a polishing film 204 in a plane perpendicular to the majorsurfaces 102, 102′ (FIG. 1) of a substrate 100 such that the edge 104 ofthe substrate 100 may be pressed against (e.g., as indicated by thestraight downward arrows 205 a, 205 b) the polishing film 204 and thepolishing film 204 may contour to the substrate edge 104. As indicatedby the curved arrow 205 c, the substrate 100 may be rotated against thepolishing film 204. The polishing film 204 may be supported by a pad 206disposed adjacent a backside of the polishing film 204 and mounted onthe frame 202. As indicated by the straight upward pointing arrow 207,the frame 202 including the tensioned polishing film 204 and/or the pad206 may be pushed against the edge 104 of the substrate 100. Thepolishing film 204 may be supported and tensioned by spools 208, 210mounted to the frame 202. A supply spool 208 may include unusedpolishing film 204 available to be unwound and pulled into positionadjacent the substrate 100 while a take-up spool 210 may be adapted toreceive used and/or worn polishing film 204. One or both of the spools208, 210 may be indexed to precisely control the amount of polishingfilm 204 that is advanced. One or more fluid channels 212 may beprovided to deliver chemicals and/or water to aid in thepolishing/cleaning of the substrate edge 104, lubricate the substrate,and/or to wash away removed material. The fluid channel 212 may beadapted to deliver fluid to the substrate 100, to the polishing film204, and/or to the pad 206.

The embodiment of FIG. 14 further includes a controller 1308 (e.g., asoftware driven computer, a programmed processor, a gate array, a logiccircuit, etc.) adapted to direct the operation of a driver 1402 whichmay be used to rotate the substrate 100. The driver 1402 may beembodied, for example, as a motor adapted to rotate a vacuum chuck,drive rollers, etc. The controller 1308 may transmit or output a controland/or power signal to the driver 1402 via a signal line 1404. Further,the controller 1308 may be adapted to receive one or more feedback orinformation signals from the driver 1402 via one or more signal lines1406. As noted above, the feedback or information signals from thedriver 1402 may provide various indications about the status of thedriver 1402, the edge polishing apparatus 202, and/or the substrate 100.For example, the rotational speed of the driver 1402 may be determinedfrom a signal that indicates the amount of current drawn by a motorwithin the driver 1402. Alternatively, a sensor (not shown) within thedriver 1402 may be employed to generate a signal indicative of thetorque of the platform (e.g., vacuum chuck) holding the substrate 100 asit is rotated by the driver 1402 and/or the energy being exerted by thedriver 1402 to rotate the substrate 100 via the platform.

The information signal(s) on the signal line(s) 1406 may be used tomonitor the polishing progress of the edge polishing apparatus 202. Forexample, a change in the current drawn by a motor within the driver 1402as indicated by a feedback signal on signal line 1406 may be interpretedby the controller 1308 as an indication that the amount of frictionbetween the edge polishing apparatus 202 and the substrate has changed.Assuming a constant force 207 is being maintained by the edge polishingapparatus 202 on the substrate 100, the controller 1308 may interpretthe change in the amount of friction to mean that different material isnow being polished. A substrate 100 that includes multiple layers ofmaterial including, for example, a film layer, may be comprised ofdifferent materials. Thus, the controller 1308 may determine that thechange in current indicated on the signal line 1406 means that a layerof material has been removed from (e.g., polished off of) the edge 104of the substrate 100. Additionally or alternatively, depending on thecharacteristics of the edge 104 of the substrate 100, the controller1308 may interpret a change in the amount of friction to mean that acertain amount of material has been removed from the edge 104 andconsequently, that the edge profile has changed.

The embodiment of FIG. 14 further includes an actuator 1408 adapted tobe directed by the controller 1308. The actuator 1408 may be used topress the pad 206 and/or film 204 against the rotating the substrate100. The actuator 1408 may be adapted to apply a constant force againstthe substrate or a variable force determined by the controller 1308. Theactuator 1408 may be embodied, for example, as a pneumatic piston, ahydraulic ram, an electric solenoid, etc. The controller 1308 maytransmit or output a control and/or power signal to the actuator 1408via a signal line 1410. Further, the controller 1308 may be adapted toreceive one or more feedback or information signals from the actuator1408 via one or more signal line(s) 1412. The feedback or informationsignals from the actuator 1408 may provide various indications about thestatus of the actuator 1408, driver 1402, and/or the substrate 100. Forexample, the amount of force applied by the actuator 1408 may bedetermined from a signal that indicates the amount of current drawn by asolenoid within the actuator 1408. Alternatively, a sensor (e.g., atransducer, not shown) within the actuator 1408 may be employed togenerate a signal indicative of the energy being exerted by the actuator1408 to apply force to the substrate 100.

As with the information signal(s) on signal line(s) 1406, the signal(s)on line(s) 1412 may be used to monitor the polishing progress of theedge polishing apparatus 202. For example, as material is removed fromthe substrate 100 and the diameter of the substrate 100 is reduced, anactuator 1408 adapted to automatically maintain a fixed amount of forceon the substrate 100 may adjust the position of, and/or applied forceto, the pad 206 and/or polishing film 204. A signal on line 1412 mayindicate this change and the controller 1308 may make a determinationthat a certain amount of material has been removed from (e.g., polishedoff of) the substrate 100 based on the signal.

The controller 1308 may use the feedback signals provided by the driver1402 to determine whether a preset endpoint for edge polishing has beenreached (e.g., a desired edge profile) and/or a difference between acurrent state of the edge 104 and the preset endpoint. For example, ifthe endpoint has been reached or the current state of the edge 104 isclose to the endpoint (e.g., as measured in an amount of material thathas been removed from the edge 104), then the controller 1308 maytransmit signals to the driver 1402 to reduce the rotation speed of thesubstrate 100 so as to, in the former case, prevent further removal ofmaterial from the edge 104 or, in the latter case, to decrease the rateat which material is removed from the edge 104. Similarly, thecontroller 1308 may use feedback signals provided by the actuator 1408to determine whether the preset endpoint has been reached or is close tobeing reached. The controller 1308 may transmit signals to the actuator1408 to reduce an amount of force applied to the pad 206 and/orpolishing film 204 to halt or slow removal of further material from theedge 104 in the event of such a determination.

The foregoing description discloses only exemplary embodiments of theinvention. Modifications of the above disclosed apparatus and methodswhich fall within the scope of the invention will be readily apparent tothose of ordinary skill in the art. For instance, although only examplesof cleaning a round substrate are disclosed, the present invention couldbe modified to clean substrates having other shapes (e.g., a glass orpolymer plate for flat panel displays). Further, although processing ofa single substrate by the apparatus is shown above, in some embodiments,the apparatus may process a plurality of substrates concurrently.Further, the edge polishing apparatus 200 of the present invention maybe integrated to other devices. For example, the apparatus 200 may beintegrated into a major surface polisher or a substrate cleaner.Integrating a edge polishing module into an output station of asubstrate polisher (e.g., the APPLIED MATERIALS, INC. Reflexion OxideCMP System) exchanger offers a number of advantages. Such integrationcan take advantage of the substrate exchanger so that no additionalsubstrate transport is required. Facilities such as de-ionized water anddrains are already resident and access to the module through thepolisher windows may be easily available. Additionally, such integrationmay be done without impacting the footprint of the tool. Further,particularly with applications which have relatively long process cycletimes such as, for example, copper applications, there is sufficienttime to polish the edges of the substrate without degrading the overallthroughput of the tool.

Accordingly, while the present invention has been disclosed inconnection with exemplary embodiments thereof, it should be understoodthat other embodiments may fall within the spirit and scope of theinvention, as defined by the following claims.

1. An apparatus adapted to apply a preset pressure to a polishing filmin contact with an edge of a substrate comprising: an actuator adaptedto apply a preset pressure to the polishing film; and a controllercoupled to the actuator and adapted to receive a signal indicative of acondition of the edge of the substrate, and to adjust a pressure appliedby the actuator to the polishing film so as to maintain the presetpressure based on the received signal.
 2. The apparatus of claim 1wherein the polishing film is adapted to conform to the edge of thesubstrate via application of the preset pressure.
 3. The apparatus ofclaim 1, wherein the signal indicates whether an endpoint has beenreached.
 4. The apparatus of claim 1, wherein the signal indicateswhether a layer of material has been removed from the edge of thesubstrate.
 5. The apparatus of claim 1, wherein the signal indicateswhether an intended edge profile has been reached.
 6. The apparatus asrecited in claim 1, further comprising: a driver coupled to thecontroller adapted to rotate the substrate against the polishing film,the driver adapted to generate a signal indicative of the condition ofthe edge of the substrate.
 7. The apparatus of claim 6, wherein thecontroller is coupled to and adapted to direct operation of the driverin response to a signal received from the at least one sensor so as toattain a preset polish level.
 8. The apparatus of claim 1 furthercomprising a friction sensor coupled to the controller and adapted toprovide a signal indicative of an amount of friction between thesubstrate and the polishing film.
 9. The apparatus of claim 8 whereinthe amount of friction between the substrate and the polishing film isindicative of an amount of material that has been removed from thesubstrate.
 10. The apparatus of claim 6 wherein the signal indicates anamount of force applied to the actuator to push the polishing filmagainst the substrate.
 11. The apparatus of claim 6 wherein the signalindicates an amount of energy being exerted to drive the substrate. 12.The apparatus of claim 1 wherein the actuator further comprises asolenoid.
 13. The apparatus of claim 12, wherein the amount of pressureapplied by the actuator is determined based on the amount current drawnby the solenoid.
 14. The apparatus of claim 1 wherein the presetpressure is at least one of constant or varied.
 15. The apparatus ofclaim 1 further comprising a head adapted to support the polishing film.16. The apparatus of claim 15 further comprising a pad mounted to thehead via the actuator, and adapted to press the polishing film againstthe substrate.
 17. The apparatus of claim 16, wherein the pad is adaptedto contour the polishing film to an edge of the substrate.
 18. Theapparatus of claim 15 wherein the actuator is adapted to push the headtowards the substrate.
 19. The apparatus of claim 16 further comprisinga fluid supply coupled to the controller, wherein a fluid is deliveredto the substrate via the pad.
 20. The apparatus of claim 19 furthercomprising one or more fluid channels, wherein the fluid channels areadapted to deliver the fluid to the pad.